Predetermined torque release hand tool



Feb. 9, 1960 o. B. HARMES 2,924,134

PREDETERMINED TORQUE RELEASE HAND TOOL fl/ angu g Q lg 4% I /5 6 j L "may INVENTOR. QPE/Y 5. #4194455 United States Patent PREDETERMINED TORQUE RELEASE HAND TOOL Oren B. Harmes, Algona, Iowa Application August 8, 1956, Serial No. 602,721

8 Claims. (Cl. 81--52.4)

' This invention relates to torque-transmitting and indicating devices. More particularly, it relates to devices designed for applying a limited and measured amount of torque to another structure.

In the field of hand tools and particularly in the field of tools such as screw drivers, socket wrenches, and the like, there has long been need for a compact and accurate tool for applying a limited and measured amount of -torque to screws, nuts, and the like. This is particularly true when the screw or bolt, which carries the thread must. be made of a material, such as aluminum, so that because of the nature of the metal there is considerable danger of stripping the thread of thescrew or bolt, or of damaging the metal in which they are embedded. Some such tools have heretofore been designed in an effort to satisfactorily solve this problem, but they have either been incapable of accurate setting to release at a predetermined torque or have been bulky, and hence inconvenient and impractical to use, or both. My invention 'is directed toward eliminating these disadvantages.

'It is a general object of my invention to provide a novel and improved device for applying a measured amount of torque to a screw, nut, or the like.

A more specific object is to provide a novel and imtool when that torque has been exceeded.

Another object is to provide a novel and improved hand tool for accurately applying a predetermined amount of torque to a screw, nut or other object, which will automatically warn the operator or user when that torque has been exceeded, and which will automatically reset itself after such a warning has been given and the .operator discontinues applying the excessive torque.

Another object is to provide a novel and improved ;hand tool of the class described, which is constructed and arranged to permit accurate adjustment, so that it will issue a warning to the user whenever a desired predetermined torque is exceeded.

Another object is to provide a novel and improved l hand tool which is constructed and arranged to issue a a ratchet type handle and which will permit accurate adjustment, so that the tool will issue a warning when- ,cver a desired predetermined torque is exceeded.

These and other objects and advantages of my inven- I tool which is convenient and practical to use as a screw driver or as a socket wrench, or as a T wrench or with for rotation about the axis of torque.

ice

- 2 tion will more fully appear from the following description made in-connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

Fig. 1 is' a perspective view of one embodiment of my invention.

Fig. 2 is a top plan view of the same with the cover thereof removed.

Fig. 3 is a vertical sectional view taken along line 3-3 of Fig. 2.

Fig. 4 is a fragmentary sectional view taken along line 4-4 of Fig. 3, and

Fig. 5 is a top plan view of a modified form of my invention with the cover removed illustrating how the invention may be utilized to break or close a circuit to a source of power which may be utilized in conjunction with my device.

One embodiment of my invention may include as shown in Figs. 1-5 a frame or metal casing, indicated generally as 6, and having preferably sidewalls 6a, 6b, 6c and 6d, a bottom wall 6e and a top wall or cover, 6 The top wall, 6 has an upstanding boss '7 with a recess 8 formed therein adapted to receive a ratchet type handle or the like. The bottom wall 62 has a depending boss 9 with an opening therethrough which rotatably supports a torque-transmitting shaft 10 upon the frame or casing 6. As can best be seen by reference to Fig. 3 the shaft 10 is rotatably mounted in the bottom wall 6e This shaft 10 depends downwardly through the bottom wall and has a reduced lower end portion 10a, one side of which carries a spring loaded steel ball 11, which adapts the lower end for receiving and retaining a socket wrench or a screw driver type adaptor. I

Pivotally mounted on the bottom wall 6e of the casing 6 upon a pivot post 12, is a lever member 13. This lever member 13 is pivoted near one of its ends and one of its end portions 13a constitutes a relatively short lever arm, while its other end portion 13b constitutes a relatively long lever arm. The lever arm 13b has an offset terminal portion 14 which is best shown in Fig. 2. This oflFset portion 14 is made of a magnetically permeable material.

Fixedly mounted in one corner of the casing 6 and immediately adjacent and opposite to the offset portion 14 of the lever 13 is a permanent magnet 15. This permanent magnet urges the lever 13 to rotate about the pivot 12 so that the offset portion 14 willcontact the magnet. The magnet 15 is of a permanent type. A characteristic of this type of magnet is that its sre'ngth remains consistent over an indefinite period of time. Thus, the force with which the offset portion 14 of the lever 13 is drawn toward the magnet 15 is a constant one and will not diminish over a period of time.

Secured to the upper end portion of the shaft. 10 which is within the casing 6 and rotating therewith, is a second lever member 16. This lever member 16 has an angulated portion 16a at its other end which engages the short lever arm 13a of the lever 13. Thus, when the user applies a torque to the casing 6 which is proportioned so as to fit comfortably Within the user's band, theresistance offered by the screw or bolt to which the shaft 10 is connected will be transmitted through the angulated portion 16a to the leverrnember 13 and the lever member 16 will tend to urge the offset portion 14 away from the magnet 15. When the resistance offered to the torque exerted upon the casing 6 is of sufficient magnitude, the offset portion 14 of the'lever member 13 will be forced away from the, magnetlfi despite the moment of force resulting from ,theq foree of attraction of the magnet 15 and the length at the .other tool' which may be required for use.

level 13b. When this takes place the .olfset por- ,-the';.m agnet il5. It is well knovm that when theelement 14 and the magnet 15 are registering with each other,

:the maximum force is exerted upon the ofls'et portion 14. I have provided means for causing the offset portion v14 toibe spaced at various positions relative-to the permanent magnet 15 and have calibrated .this means so that the .tool may be set so as to issue the audible warning hereinbefore described at any desired predeter- :m'ined :torque." .To' accomplish this purpose, I have threaded a camming member 17 into the medial portion of the lever member 13 and :this camming member -ex tends outwardly through an, opening provided therefor .inthe side wall 6d of the casing. Threadedly mounted .onthe exterior of the side wall 6d is a calibrated nut 18. This nut 18 is threaded on a lock nut 19, which in :turnis threaded into alaterally extending boss 20. The "cam member 17 is positioned relative to the calibrated .nut 18 so ,that as the nut .18 is turned on the lock nut .19 the nut 18 will bear against the camming member .17 and force the offset portion 14 of the lever 13 away from the magnet 15 or permit it to be drawn toward the magnet 15, depending upon the direction the nut 18 is turned. As previously described the nut .is calibrated so that it maybe set at any desired predetermined torque and once it is so set it may be lockedin this position by :merely tightening the .lock nut 19.

Fig. shows a modified form of my invention. It is constructed exactly as the structure shown in .Figs. 1-4, except that there is an embellishment added in the form of a switch .21 having lead wires 22 and 23 connected thereto, the latterof which lead to a source of rotary power, which may be connected to the tool. This switch is normally in closed position but moves to open posi- In use, a socket wrench may be attached to the shaft at the lower end thereof, and retained thereon by the spring loaded ball 11. In lieu thereof, a screw driver :adaptor may be applied in the same manner or some Once' the tool has been snapped onto the lower end of the shaft 10, the device is ready for applying torque as desired.

It will be readily seen that the device maybe utilized as i .a screw driver with the casing 6 functioning as a handle when so used and when a screw driver attachment has been applied to the lower end of the shaft 10. 'To set .the device to issue an audible warning when a predetermined torque is exceeded, the user merely loosens the lock screw 19 and adjusts the calibrated nut 18 to the desired point. Adjustment of the calibrated nut 18 varies the depth to which the camming memberg17 is forced inwardly and thereby the spacing between the magnet and the permeable offset portion 14 ofjthe lever 13 is varied. By increasing the spacing between the offset portion 14 and the magnet 15 theamount of torque required to-cause the oflfset portion to swing away from the magnet 15 is reduced. By reducingthe spacing between these two members, the amount ofgtorque required to cause the oitset portion 14 to swing "away from the magnet is increased. It will be readily appreeiated that the force exerted by the lever member 16 on theshor't l-everarm 13a is responsiblefor causing .therelatively long lever arm 13b-to swing inwardlyso that the offset portion 14 will slap against the side walls of the casing 6. When this occurs, an audible signal 1s produced which warns the user that the predetermined.

torque has been exceeded and he may then terminate the application of torque to the. casing 6.

If desired, a ratchet Thandle may be applied to the casing 6.at the opening 8, so as to substitute the ratchet handle"for the application of torque manually to the casing 6.

It should be aimed that the offset portion 14 is disposed relative to the axis of torque (which is the axis "the receptacle 8 provided for that purpose.

the tool to be compactly constructed and to make it convenient and practical for'everyday use.

It will also be noted that, there is a ballbearing or steel ball 24 which is disposed between the top of "the shaft 10 which is inside the casing 6 and the underside of the cover 6f of the casing. The purpose of this ball is so as to substantially reduce any inaccuracies which might occur as aresult of substantial pressure downwardly bythe userupon theplate 6f.

It will also abeireadily appreciated that this device may be utilizedsas a T wrench milieu of a screw driver or pocket Wrench. Also the tool may be quickly and readily 'attachedto a source of rotary power such as an electric motor which could be utilized to rotate the tool.

about the axis of the shaft 10 by connecting the same at In this latter event the construction shown in Fig. 5 could be utilized with the wires 22 and .23iuterposed within .the 1 electrical circuit running to the source of rotary power so that when the offset portion 14 swings away from the magnet .15 the circuit will be broken when the switch 21 is depressed. This would shut off the source of current to the motor and thereby .prevent additional torque be ing applied to the item to which the tool-is connected.

Thus it can beseen that I have provided a novel hand tool which will accurately apply a predetermined amount of torque to a screw or nut, or other object, and which will automatically warn the operator or user when predetermined torque has been exceeded. An audible signal is created when the offset portion 14 slaps against the side wall of the casing 10. It will readily be appreciated that other sounding means could be provided as a substitute forthe .wall of a casing 6, but it is found that the casing 6 provides ample means for adequtely warnbe noted that my tool is compact and convenient and.

practical to use. The entire mechanism is built intoa small casing set which fits the hand of the usercomfortably-and does not require a large amount of space for its use. Moreover, the device is simple and practical to manufacture and utilize, and therefor constitutes a substantial improvement over any tool heretofore designed within my knowledge. 7

It will, of course, be understood that various changes may be made in theform, detail, arrangement and proportion of the parts without departing from the scope of my invention.

What I claim is: g

l. A torque-applying and .indicating device comprising aframe, a torque-transmitting element rotatably mounted on said frame for relative movement about the axis of torque, a lever member ,pivotally mounted on said frame adjacent said torque-transmitting element and having a magnetically permeable portion removed from itsaxis of magnetically permeable portion of said lever and normitting element and rotatable therewith and engaging a portion of said lever to cause the same to pivot and urging said magnetically permeable portion of the latter away from said magnet, whereby said magnetically permeable portion will swing away from said magnet when a predetermined torque is applied to said torque-transmitting element, and metallic sounding means carried by said frame adjacent said lever in the path of the swinging.

movement of said lever, whereby an audible signal will be created by said lever striking said sounding means when said lever swings away from said magnet as a result of the application of said predetermined torque to said torque-transmitting element.

2. A torque applying device comprising a "frame, a torque-transmitting element rotatably mounted on said frame for relative movement about the axis of torque, a lever member pivotally mounted on said frame adjacent said torque-transmitting element and having a magnetically permeable portion removed from its axisof pivot, a magnet fixedly mounted on said frame adjacent said magnetically permeable portion of said lever and normally holding the same adjacent thereto and against pivoting, mechanical means connected with said torquetransmitting element and rotatable therewith and constructed and arranged to operatively engage a portion of said lever to cause the same to pivot and urge said magnetically permeable portion of said lever away from said magnet when torque is applied to said element, whereby said magnetically permeable portion will swing away from said magnet when a predetermined torque is applied to said torque-transmitting element, and adjustable spacing means carried by said frame and engaging said lever and constructed and arranged to vary the space between said magnet and said magnetically permeable portion of said lever, whereby the magnitude of the predetermined torque required to be applied to said torque-transmitting element to cause the magnetically permeable portion to swing away from said portion may be varied, said spacing means including a cam member movably mounted on said frame and engaging said lever member at a point removed from its axis of pivot, and constructed and arranged to vary the spacing between said magnet and said magnetically permeable portion when said cam is moved, and calibrated means carried by said frame for controlling the movement of said cam member to enable said device to be set so as to cause said magnetically permeable portion of said lever to swing away from said magnet at a desired predetermined torque.

3. A torque applying device comprising a frame, a torque-transmitting element rotatably mounted on said frame for relative movement about the axis of the torque, a lever member pivotally mounted on said frame and operatively connected wtih said torque-transmitting element and having lever arms of fixed length and having a magnetically permeable portion removed from its axis of pivot, a magnet carried by said frame adjacent said magnetically permeable portion of said lever and normally holding the same adjacent thereto and against pivoting, said permeable portion being movable into spaced relation with said magnet, and screw controlled adjustable camming means mounted on said frame and engaging said lever and constructed andarranged to vary the spacing between said magnet and said magnetically permeable portion of said lever, wherebygthe magnitude...

of the predetermined torque requiredutocause said, magnetically permeable portion to swing away from said magnet may be varied.

4. The structure defined in claim 3 wherein said camframe and bearing against said cam member an constructed'and arranged to force said cam I r I wardly relative to-said frame and thereby vary the spacing between said magnet and said magnetically permeable portion of said lever.

5. A torque applying device comprising a frame, a

torque-transmitting element rotatably mounted on said frame for relative movement about the axis of torque, a

1 lever member pivotally mounted on said frame adjacent said torque-transmitting element and having a magnetically permeable portion removed from its axis of pivot, a magnet carried by said frame adjacent said magnetically permeable portion of said lever and normally holding the same adjacent thereto and against pivoting, mechanical means connected with said torque-transmitting element and rotatable therewith and engaging a portion of said lever to cause the same to pivot and urge said magnetically permeable portion of the latter away from said magnet, whereby said magnetically permeable portion will swing away from said magnet when a predetermined torque is applied to said torque-transmitting element, and adjustable spacing means carried by said frame and engaging said lever and constructed and arranged to vary the spacing between said magnetically permeable portion of said lever and said magnet, whereby the magnitude of the predetermined torque required to be applied to said, torque-transmitting element to cause said magnetically permeable portion to swing away from said magnet may be varied.

6. A torque applying device comprising a frame, a torque-transmitting element rotatably mounted on said frame for relative movement about the axis of torque, a lever member pivotally mounted on said frame and operatively connected with said torque-transmitting element and having a magnetically permeable portion removed from its axis of pivot, a magnet fixedly mounted on said frame adjacent said magnetically permeable portion of said lever and normally holding the same adjacent thereto and against pivoting, said torque-transmitting element through its operative connection with said lever urging the same to pivot when torque is applied to said element and urging said magnetically permeable portion of said lever away from said magnet, whereby said magnetically permeable portion will swing away from said magnet when a predetermined torque is applied to said torquetransmitting element, and adjustable spacing means carried by said frame and engaging said lever and being movable transversely of said lever to vary the spacing between said magnet and said magnetically permeable portion of said lever, whereby the magnitude of the predetermined torque required to be applied to said torquetransmitting element to cause said magnetically permeable portion to swing away from said magnet may be varied.

7. A torque applying device comprising a frame, torque-transmitting means rotatably mounted on said frame, a lever pivotally mounted on said frame and having lever arms of fixed length one of which is operatively connected with said means and the other of which carries a magnetically permeable element, a magnet carried by said frame adjacent said magnetically permeable element and normally holding the. same adjacent thereto and thereby precluding rotational movement of said means, and

adjustable spacing means carried by said frame and havaid magnet may; be variedl' riiearis to, cause magnetically permeable portion to swing away fro I A torque applying device comprising a frame memframe, a leve'rmember pivotally mounted on said frame ber, torque-trans rnitting means rotatably mounted on said member's d operatively connected with said means,

whereby tqrqne applied to said means will urge said levlenv .mernbertq ivot in a predetermined direction, a magnett carried byone -of said members and spaced from the T O f pivot of said lever member, a magneticallypermeable "element'earrie'd by the other'of said members direc'tlyropposite said magnet and normally en'gaging'the sameto said lever member and engaging the same to vary the spacing between said magnet and said magnetically lpermeable element, whereby flhe magnitude ofthe torque required to be applied to said torque-transmitting means to cause the force of said magnet on said magnetically permeable element to be overcome may bevaried.

. "UNITED STATES PA ENTS Morris o mew, 1944 Johnson May 1, 19 57 Paterson Nov. 12, 1957 FOREIGN PATENTS Germany 'Oct. 29, 1909 a 

